AMCC ART Day, Saturday 9 November 2013

[nzspokes]

My thoughts on Phil's crash:

There are only 2 left hand corners at Hampton and the downhill left hander is a proper corner. The first left hander is just a kink. So tyre temperature (lack thereof) may have been a factor still. The corner is a downhill one with a decreasing radius as you come to the end and this does really test front end grip so there may have been a combination coming into effect - a rearwards shift in body position, a counter steer load increase as the corner tightens, an increasing throttle opening and a cooler tyre all combining to give a front end washout.

I do not agree with an over filled reservoir as being the likely cause because if the reservoir was overfilled the problem would have been very apparent on the ride to the track itself or in one of the earlier sessions. Overfilled reservoirs mean that the pads are kept in contact with the disc and so as things get hotter and hotter the problem compounds very quickly - the ride to the circuit is far longer than any of the sessions at the circuit and so the front brakes would have locked on before Phil arrived. Even if they hadn't done so on the ride there unless Phil was barely using his brakes in sessions 1 and 2 and then was hitting them really hard early in session 3 the problem would have been evident in an earlier session. And with Phil in the kitty litter the front brakes would have been glowing with heat.

It is also possible that the jar of the crash caused a calliper piston to stick briefly or a bit of the litter wedged briefly in the front brake lever housing and jammed the lever. This litter was dislodged when the fiddling with the lever occurred.

Contamination is also unlikely in my opinion - again the problem would be very unlikely to manifest itself by making a brake suddenly come on - it is rather more likely to make the brakes fail rather than work excessively well.

So, sorry Phil,

Pilot error.

I wish to disagree that over filling the reservoir could not be a fault. You would not be braking in the same manor on road riding as a general rule and the brakes would heat more than normal. Now if the fluid was overheating it could have been causing the brake to bite earlier in the lever stroke, so when the rider goes to use a little brake the lever bites earlier than normally expected. That could bring the rider down in the wrong situation. I don't believe the brakes were locked on as such just an earlier bite point.

But this is just one potential reason for the incident. Rider error is most likely but the brake does need to be checked.

[vinducati]

I don't really think at such a low speed the front would go unless the brakes were on.
But me, I am not an expert.
Sucks though

[nzspokes]

Was there a photograher there?

[Voltaire]

I do a bit of classic racing on my BMW R90 with lap times of around 1m27. Recently added RaceChrono to my phone and it records each lap green on accelerating and red on deceleration with high and low speed markers.
42 kmph was the fastest I get around the hairpin.( 166 past the start/finish)
At that speed with braking finished and light throttle I'm going to go with brake lockup.
My tyres are 4 years old, Bridgestone BT45's running 27 psi f/r, I can scrape the head on T6 so I don't think tyres are an issue.
I have had car brake lines in the past that would let pressure to the calipers but were starting to perish internally and slow to release the pressure.

[p.dath]

I got to go and see my bike today. I felt very nervous before hand, but is has been strangely calming.

The brake fluid reservoir is just fine. It is not over filled.

As MarkW says, it has simply been a case of pilot error. I think I simply carried too much lean angle around the corner for the speed I was going, and lost the front end. It sounds simple enough when I say it to myself.


There was another bike parked near mine they had also been in an accident. I was told that the rider was in pretty bad shape. And here I stand with not even a scratch on me.


Thanks for your support everyone. I've had a lot of positive feedback.